The present invention relates to drive devices for use in packaging machines, for example, for intermittently transporting containers, filling contents into the containers during transport and sealing off the filled containers, the drive device being adapted to drive an operating member for the packaging operation.
Already known as such drive devices are those comprising mechanical means such as a cam, those comprising a servo motor or like motor and those comprising a fluid pressure actuator such as an air cylinder.
Drive devices wherein a cam or like mechanical means is used are suitable for causing an operating member to perform an accurate movement but have the problem of being complex in construction or requiring labor and time for altering the operation curve.
Drive devices comprising a servo motor of like motor permit an accurate movement, are usable with an altered operation curve which is easy to prepare, and are therefore placed into use in recent years in place of drive devices comprising a cam or like mechanical means. However if many drive devices comprising a servo motor or the like are used, there arises the problem that the packaging machine becomes expensive in its entirety.
Although inexpensive, drive devices comprising an air cylinder or like fluid pressure cylinder are not comparable to the drive devices of the above two types with respect to operation stability, require much labor for adjustment and therefore have the problem that the operating members usable with the drive device are limited.